@article {freue2013natural,
	title = {A natural robustification of the ordinary instrumental variables estimator},
	journal = {Biometrics},
	volume = {69},
	number = {3},
	year = {2013},
	pages = {641{\textendash}650},
	publisher = {Wiley Online Library},
	author = {Freue, Gabriela V Cohen and Ortiz-Molina, Hernan and Zamar, Ruben H}
}
